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Dynamic vitamin D can help prevent a host of ills

FARGO - Vitamin D is something of a wonder drug, but bad things can happen if your body isn't getting enough. Those who get adequate levels of vitamin D are better able to ward off everything from cancer to heart disease to autoimmune disease.

But here's the problem: Studies show that many, many people - especially in northern latitudes - don't get enough of the vital nutrient, which acts in the body like a hormone.

In fact, it's very difficult and practically impossible to get enough vitamin D from your diet. Very few foods, except cod-liver oil, naturally contain vitamin D.

Since the late 1940s, milk has been fortified with vitamin D. More recently, other dairy foods, including yogurt, and some orange juice contain the vitamin as an additive as well.

But Cathy Breedon, a clinical and metabolic nutrition specialist at Sanford Medical Center in Fargo, says people would have to drink quarts a day to get enough vitamin D.

Although sunshine enables the body to produce vitamin D, few people get enough safe exposure to the sun.

So that means taking multivitamins with vitamin D and often supplements.

The question therefore becomes: How much vitamin D do I need to take?

The short answer: More than was recommended until recently, and many experts would argue that still more is needed than is officially recommended.

D helps immune system

A little history about how vitamin D came to be added to our milk helps to explain how the old recommendations came to be.

For years people knew that the way to prevent rickets, a softening of the bones in children, was to take cod-liver oil. Once it was discovered that vitamin D was the preventive ingredient, vitamin D was added to milk, starting in the late 1940s - one of the United States' first public health interventions.

Since then, as health science has advanced, researchers have come to understand the vital role vitamin D plays in helping prevent a raft of diseases and conditions.

One reason vitamin D deficiency is implicated in so many diseases: More than 200 tissues in the body have receptors for it, indicating its widespread importance.

Another reason is that vitamin D is important to help the immune system work properly.

"The inadequacy of this hormone allows bad things to happen," Breedon said.

The amount of vitamin D that can prevent rickets in children - 400 international units, or IU, daily - became the recommended daily allowance for everyone, adults included.

"This area was the rickets belt," Breedon said, referring to the northern tier of states, now recognized as an area at risk of vitamin D deficiency because of the lack of adequate sun, a result of its low angle.

The problem, Breedon said, is the assumption the amount of vitamin D that would protect children from rickets was all that was required, an orthodoxy that lasted for decades until broken down by a barrage of research.

As a result, an expert committee of the Institute of Medicine last fall set a new "dietary reference intake" for vitamin D, setting higher levels.

For instance, an adequate intake for infants up to 6 months is 400 IU daily, with a maximum safe daily upper-level is 1,000 IU, which rises to 1,500 for infants age 6 to 12 months.

For those ages 1 to 70, the adequate daily intake under the expert recommendations is 600 IU, with daily maximum safe upper levels ranging from 1,500 IU for children ages 1 to 3 and 4,000 IU for ages 9 to 70. Those 71 and older should get 800 IU daily, with a safe maximum of up to 4,000 IU per day.

Some experts argue, however, that even those recommendations are too conservative. Some studies Breedon cites say a 2,000 IU daily intake is safe and may be necessary in some cases.

The key, she added, is that people shouldn't assume that they're getting the recommended level. Some people, because of a disease, advanced age or medication, can have difficulty absorbing enough vitamin D.

"Don't assume," she said. "Assure."

That means having your doctor run a lab test to measure vitamin D in the body. Some of her patients have required much higher-than-normal doses to get adequate levels.

"Vitamin D measurement is the No. 1 assay in medicine today," she said.

Autism linked to D?

Some researchers suspect the development of autism might involve inadequate amounts of vitamin D, especially for children who are conceived in winter, when vitamin D levels are likely to be at their lowest.

Interestingly, Breedon said, the rise in the incidence of autism coincides with the greater awareness of the need to avoid too much sun exposure, which damages the skin and can cause skin cancer.

The drumbeat of research confirming the importance of vitamin D is also reflected in Breedon's encounters with patients. It's not unusual for them to say, "I used to get sick all the time and now I'm not," she said. "I see that all the time."

It's taken time for the importance of vitamin D to register, both within the medical profession and the general public, in large part because there is no pharmaceutical industry to tout it.

"You can't patent vitamin D," Breedon said. "God made that. So you don't see a lot of ads on TV."

Although a big proponent of vitamin D, Breedon makes it clear that it's important for people to eat a healthy diet and to make sure they are getting adequate amounts of all recommended vitamins and minerals.

"You need everything to do everything," she said.

Who needs the D?

Certain people are at greater risk for vitamin D deficiency:

* Children of all ages.

* Pregnant and nursing women.

* Obese people.

* Darker-skinned people, especially those of African or Hispanic descent.

* Anyone with a malabsorption syndrome, such as cystic fibrosis, Crohn's disease or inflammatory bowel disease.

* Anyone who has had bariatric surgery.

* Anyone with osteoporosis, osteomalacia, or an elderly person who's had a fall or fracture.